Method and arrangement for receive power estimation in a mobile radio communications system

Abstract

The present invention relates to a method and apparatus for estimating a received signal power of a first transmission channel at a receiving node in a communications system wherein a received signal comprises information transmitted by a transmitting node over at least two transmission channels. The received signal power of a second of the at least two transmission channels is measured, and together with an estimate of the relationship between the transmission power of the second transmission channel and the transmission power of the first transmission channel; the measurement of the received signal power is used in estimating the received signal power of the first transmission channel.

The invention claimed is: 
     
       1. A method of estimating a received uplink signal power of a first transmission channel at a receiving node in a communications system, wherein the receiving node is a base station, wherein a received signal comprises information transmitted by a transmitting node over at least two transmission channels, wherein the transmitting node is a mobile station, the method comprising:
 measuring the received uplink signal power of a second of the at least two transmission channels; 
 estimating a relationship between the transmission power of the second transmission channel and the transmission power of the first transmission channel; and 
 estimating the received uplink signal power of the first transmission channel using the measurement of the received uplink signal power of the second transmission channel and said estimated relationship; 
 measuring the received uplink signal power of at least one further transmission channel; 
 estimating a relationship between the transmission power of the further transmission channel to the transmission power of the first transmission channel; and 
 wherein estimating the received uplink signal power of the first transmission channel further comprises using the received uplink signal power of the at least one further transmission channel and the at least one estimated relationship between the transmission power of the first and further transmission channels. 
 
     
     
       2. The method of  claim 1 , further comprising
 measuring the received uplink signal power of the first transmission channel; and wherein 
 estimating the received uplink signal power of the first transmission channel further comprises using the measured received uplink signal power of the first transmission channel. 
 
     
     
       3. The method of  claim 1 , wherein
 the receiving node employs interference cancellation; and 
 the measurement(s) of received uplink signal power is performed prior to interference cancellation. 
 
     
     
       4. A method of estimating a received uplink signal power of a first transmission channel at a receiving node in a communications system, wherein the receiving node is a base station, wherein a received signal comprises information transmitted by a transmitting node over at least two transmission channels, wherein the transmitting node is a mobile station, the method comprising:
 measuring the received uplink signal power of a second of the at least two transmission channels; 
 estimating a relationship between the transmission power of the second transmission channel and the transmission power of the first transmission channel; and 
 estimating the received uplink signal power of the first transmission channel using the measurement of the received uplink signal power of the second transmission channel and said estimated relationship; 
 wherein
 estimating a relationship comprises estimating the ratio of the transmission power of the second or further transmission channel to the transmission power of the first transmission channel, thereby obtaining a scaling factor of the second or further transmission channel; and 
 estimating the received uplink signal power of the first transmission channel is performed by applying said scaling factor of the second or further transmission channel to the measured value of the received uplink signal power of said second or further transmission channel, thereby obtaining a channel specific estimator of said second or further transmission channel, and by estimating the received uplink signal power of the first transmission channel in dependence on said channel specific estimator. 
 
 
     
     
       5. The method of  claim 4 , further comprising
 receiving, from the transmitting node, the ratio of the transmission power of the second or further transmission channel to the transmission power on the first transmission channel at at least one previous point in time; and 
 determining the scaling factor of said second or further transmission channel in dependence on said ratio at at least one previous point in time. 
 
     
     
       6. The method of  claim 4 , wherein the ratio of the transmission power on the first and second transmission channels can only take a limited number of values, and wherein
 estimating the ratio comprises determining the ratio of the measured value of the received uplink signal power of the second or further transmission channels to the measured value of the received uplink signal power of the first transmission channel; 
 comparing said determined ratio of the measured values to the limited number of values that the ratio of the transmission powers can take; and 
 estimating the ratio as the one of the limited number of values that best corresponds to the determined ratio. 
 
     
     
       7. The method of  claim 4 , further comprising:
 determining a weight coefficient for a channel specific estimator used in estimating the received uplink signal power of the first transmission channel, the weight coefficient reflecting the reliability of the channel specific estimator; and wherein 
 the estimation of the received uplink signal power of the first transmission channel is performed in dependence on said weight coefficient. 
 
     
     
       8. The method of  claim 7 , wherein
 said determining a weight coefficient includes at least initially assuming that the weight coefficient is proportional to the square of the scaling factor by use of which the channel specific estimator has been obtained. 
 
     
     
       9. The method of  claim 7 , wherein
 said determining a weight coefficient includes at least initially assuming that the weight coefficient is proportional to the inverse of the variance of a measurement error of the measured value of the received uplink signal power of the transmission channel to which the channel specific estimator relates. 
 
     
     
       10. The method of  claim 7 , further comprising
 comparing the most recently obtained value of the channel specific estimator with at least one previously obtained value of the channel specific estimator the comparing resulting in a time variation result; and 
 determining, based on the time variation result, whether the initially assumed value of the weight coefficient should be adjusted. 
 
     
     
       11. The method of  claim 7 , further comprising
 comparing the value of one second or further channel specific estimator with at least one value of another second or further channel specific estimators, the comparing resulting in a transmission channel variation result; and 
 determining, based on the transmission channel variation result, whether the initially assumed value of the weight coefficient should be adjusted. 
 
     
     
       12. A received uplink signal power estimator adapted to receive a signal comprising information transmitted by a transmitting node over at least two transmission channels, wherein the transmitting node is a mobile station, the received uplink signal power estimator being adapted to estimate a received uplink signal power of a first of said transmission channels,
 wherein the received uplink signal power estimator is adapted to measure the uplink signal power of at least a second of said transmission channels, to estimate a relationship between the transmission power of the second transmission channel and the transmission power of the first transmission channel; and to estimate the received uplink signal power of the first transmission channel based on a result of the measurement of the uplink signal power of the second transmission channel and said estimated relationship; 
 wherein the received uplink signal power estimator comprises:
 a received uplink signal power detector adapted to measure the received uplink signal power of a second of said at least two transmission channels and to generate a signal indicative of the measured received uplink signal power; 
 a scaling mechanism connected to an output of the received uplink signal power detector and adapted to receive the signal indicative of the measured received uplink signal power, the scaling mechanism being further adapted to
 determine a scaling factor based on an estimation of the ratio of the transmission power of the second transmission channel to the transmission power of the first transmission channel; 
 estimate the received uplink signal power of the first transmission channel by applying the scaling factor to measured received uplink signal power, thereby generating a channel specific estimator; and 
 generate a signal indicative of the channel specific estimator. 
 
 
 
     
     
       13. The received uplink signal power estimator of  claim 12 , wherein the received uplink signal power estimator is adapted to measure the received uplink signal power of at least two of said transmission channels and to generate corresponding channel specific estimators, the received uplink signal power estimator further comprising:
 a weight coefficient generator adapted to receive a signal indicative of a measurement of the received uplink signal power and/or the channel specific estimator of a transmission channel, and to generate a weight coefficient for the transmission channel; and 
 wherein the received uplink signal power estimator is further adapted to performe the estimation of the received uplink signal power of the first transmission channel in dependence on said weight coefficient. 
 
     
     
       14. A radio base station comprising the received uplink signal power estimator of  claim 12 . 
     
     
       15. A non-transitory computer program product comprising instructions which, when executed, perform the acts of  claim 1 . 
     
     
       16. A non-transitory computer program product comprising instructions which, when executed, perform the acts of  claim 4 . 
     
     
       17. A base station of a communications system which receives a received signal comprising information transmitted by a transmitting node over at least two transmission channels, the transmitting node being a mobile station, the base station comprising:
 a detector configured to measure the received uplink signal power of a second of the at least two transmission channels and uplink signal power of at least one further transmission channel; 
 a processor configured to:
 estimate a relationship between the transmission power of the second transmission channel and the transmission power of the first transmission channel; 
 estimate the received uplink signal power of the first transmission channel using the measurement of the received uplink signal power of the second transmission channel and said estimated relationship; 
 estimate a relationship between the transmission power of the further transmission channel to the transmission power of the first transmission channel by using the received uplink signal power of the at least one further transmission channel and the at least one estimated relationship between the transmission power of the first and further transmission channels.